7 Answers
7

"Time is over" seems to refer to time as a period that has passed. "Time is up" seems to refer to time as a certain deadline that has been reached. So when one says that the time to submit applications is over, it means that the opportunity to submit an application is missed, and when one says that the time is up, it means that you should submit your application ASAP, since it is your last chance.

I think 'time is up' is more recent, more immediate and so tends to refer to the moment of reaching a deadline or soon after i.e. still relevant, while 'time is over' is more broad and general and so tends to refer to a period of time that is in the past and not of current relevance. The immediateness of 'time is up' is what I think gives it its relative abruptness and so its negativity in some contexts.

They both express the same essential meaning: A period of time has ended.

The connotations of the two are slightly different. "Time's up" is very similar to the phrase "time's run out." It conveys an environment where time is a limited resource and someone is attempting to accomplish a particular task before the resource is used up or runs out.

Time's up! Put your pencils down and pass your exams forward.

I barely finished my exam before time was up.

"Time is over" signals the end of a longer period; one that could have conceivably lasted forever. If it is associated with a deadline for a particular task than the deadline is not typically rushed -- the allotted amount should be more than enough time to complete the task.

This usage is very similar to phrases such as "time has ended" or "time has gone" or even "from another time."

"Time is over" seems to be somewhat rarer. I see a few examples from a quick Google in contexts like:

The time for you to submit your applications is over (the opportunity or time period has passed)
Break time is over for Congress (the time period being described has ended)

So "time is over" can apply to both longer fixed time periods (many days or more) and is used with phrases like "break time" or "excuse time", whereas "time is up" typically means that a short time period has expired, such as to complete a test, and only seems to be used for periods of a few hours or less.

I would say that '(the) time is up' is more informal and emotional than '(the) time is over'.

For that reason Your time is up! (as in playing a game) is going to be more common than Your time is over! and "The time period for applications is over" is going to be more common than "The time period for applications is up." ("The time period for applications has passed" is even better in my view.)

Also notice the following contrast: "Your time at the company is up" is more threatening or at least more dismissive than "Your time at the company is over."

Similarly 'X's time is up' is a somewhat rude euphemism for the idea that somebody is about to die; you can even use it to make a threat ("Your time is up!"). That can't be done with over.

'Time is up' is used to show that the time allocated in carrying out an activity has ended and you should therefore stop and submit it wherelse the phrase 'Time is over' means that the long time allocated in carrying out an activity and submitting has ended thus the whole of the work/activity is rendered useless and of no significance.

i think time is up refer to the term "up" which means thoroughly.i.e the period of time is well expired .E.g i have to put an end to a class at five sharp so, i say to the students "time is up". whereas, the term over is refer to something more .so , time is over implies that a\some minutes are just added.

You could improve this question (and perhaps attract upvotes!) in two ways: use conventional spelling, grammar, and punctuation (i.e. write more carefully), and, much more importantly substantiate your position with references to reliable authorities. SE is very different from other Q&A sites; unvarnished opinions don't do well here.
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Dan BronApr 17 at 18:56